1. Field of the Invention
The present invention relates to a tool holder. More particularly, this invention relates to a tool holder capable of supplying a fluid such as a coolant to a processing site between a tool tip and an article to be processed.
2. Description of the Related Art
Upon processing of articles by means of tools such as drilling and milling machines, various tool holders have been conventionally used which are capable of supplying fluids such as coolants at a processing site between the tip of a tool and an article to be processed.
An example of such a tool holder is disclosed in the official gazette of the Japanese Utility Model Laid-Open (Kokai) Publication No. HEI 7-17452. This tool holder is constructed in a manner such that it comprises: a holder body with a coolant passage formed therein; a collet to be mounted at the inside diameter portion of the holder body; a nut screwed at the holder body and for fixing the collet; and a nozzle disk provided between the nut and the tool and having a plurality of nozzle holes opened toward the tip of the top end of the tool or a clearance formed to provide a predetermined space from the outside peripheral portion of the tool.
This tool holder is constructed in a manner such that a coolant supplied into the coolant passage of the holder body will pass through the inside diameter portion of the holder body and slittings of the collet and will jet out of the plurality of nozzle holes or the clearance between the tool and the nozzle disk toward the tip of the tool.
With this tool holder, an O ring is provided, as a sealing member for preventing leakage of the coolant, at the back end of an engagement portion of the nut with the nozzle disk and between the tool and the nozzle disk.
Generally, there are various kinds of tools with regard to the shape of blades and the size, and processing conditions variedly differ depending on the shape or processing depth of an article to be processed. Regarding the tool holder as disclosed in the above-mentioned official gazette, if tools with different diameters are used, the tool holder will not be able to adjust to such tools and there is a possibility that the coolant might leak from between the tool and the nozzle disk. There is also a problem in that the sealability of the tool holder is weak for the supply of a coolant of high pressure.
In addition to the above-mentioned official gazette, examples of a conventional tool holder (device for supplying fluids to a tool) are disclosed in the Japanese Patent Laid-Open (Kokai) Publication No. HEI 7-51982, the Japanese Patent Laid-Open (Kokai) Publication No. HEI 6-277916, the Japanese Utility Model Laid-Open (Kokai) Publication No. HEI 6-27046, the Japanese Utility Model Laid-Open (Kokai) Publication No. HEI 1-170531 and the Japanese Utility Model (Kokoku) Publication No. HEI 7-18515. Regarding any of these tool holders, adaptability to tools with different diameters and an improvement of sealability upon supply of a coolant of high pressure are not properly taken into consideration.